With the development of a Long Term Evolution (LTE) network, a trunking service has been implemented on the LTE network. On an LTE network, after a user equipment (UE) is attached to the LTE network, if there is no service request for a long time, the UE enters an idle (RRC_IDLE) state; and after a service request arrives, the UE initiates a radio resource control (RRC) connection, so that the UE enters a connected (RRC_CONNECTED) state. In the RRC_CONNECTED state, a UE may choose to listen to a radio channel at some moments by using a discontinuous reception (DRX) mechanism and enters a sleep state at some moments, so that power consumption of the UE can be reduced. When no service arrives for a long time, the network releases the RRC connection to the UE, so that the UE returns to the RRC_IDLE state; and in the RRC_IDLE state, the UE may listen to a calling channel and a broadcast channel according to a DRX cycle, where the DRX cycle is also called a paging cycle of the UE, and a value of the DRX cycle is generally at a level of seconds.
For a UE that needs to quickly initiate a trunking service, a transition time from the RRC_IDLE state to the RRC_CONNECTED state cannot meet a delay requirement for quickly establishing a trunking service.